Where every IC have its own tab. cells marked in grey are terminationpoints of each pin. if you only follow all grey cells. you have checked every trace on the board without checking one double trace.

Anyway, this still was a quite slow process. especially when I was unable to check any specific via or so. So being one week on a businesstrip I decided to do the backtrace again, this time I have found a Electronics CAD program that allowed me to use a scanned picture as background. It is not the best program in the world, but it works.

This is free for you to use. you can either buy the software or use the testversion to point on any via and see where it goes. I would recomend you to use the “test” function as it is a very nice feature.

BUT! I will not recomend you to produce any PCBs out of this, vias can be too close, traces too close etc. and inner layers (GND/VCC) are just actually made to show that they are connected. no real designthinking behind it. it will be too thin traces, badly connected or so. So simple: you are on your own.

When you have checked all traces. there is sometimes issues with the GALs.

There is also a hack to remove 2 waitstates improving memoryspeed. this CAN be instable if you use a quaddoubler. but works fine with 040-060 adaptes. (or 040)
Hack is made by speedgeek and can be downloaded from: www.hertell.nu/webfiles/A3640_ST_MOD.zip

Anyway. enjoy this and hope you have good use if this. It was a hard thing and a very aching back but helpful for me and hopefully for all of you out there.

UPDATE!!

I have now did a tidy up. and changes. .so that is why I do not change the original files.

So I continued my project some and did take a dead A3640 board with heavy leakge. SANDED off all print and scanned it and got:

Top:

Bottom:

I checked traces so they wasn’t too close (hopefully) and drillholes.
also I did some changes doing the delay line hack so you can overclock the board.
Adding possability of having both types of oscillators. adding some text etc.

Still GND/VCC planes might be SHIT! I am no hw designer. but hopefully it will WORK!

I haveyet again done some modifications to the board and this I guess will be the FINAL version. Rev 3.3.2
Changes: removed the J100 jumper as the machine did not start without jumpers installed anyway and JT100, same there.
Also for R101, the delayline you can now choose what pad to use for 5 or 10ns delay.
Also added values for all components on the silkscreen.
AND! actually found a function for proper GND/VCC planes, so no more traces but while planes for that.